Recurrent nontraumatic acute subdural hematoma secondary to ruptured accessory meningeal artery aneurysm: A case report and literature review
Article information
Abstract
Spontaneous acute subdural hematoma (aSDH) is an uncommon neurosurgical emergency, and aneurysms of the accessory meningeal artery (AMA) are an exceptionally rare cause. We report a case of recurrent spontaneous aSDH attributed to rupture of an AMA aneurysm, which was identified as the most likely source of both the initial and recurrent hemorrhages, successfully treated with endovascular embolization. A 36-year-old hypertensive man presented with progressive headache and drowsiness without preceding trauma. Computed tomography (CT) demonstrated a left convexity acute-on-chronic subdural hematoma with significant mass effect, while CT angiography revealed no vascular abnormality. Emergency decompressive craniectomy and hematoma evacuation were performed, but no bleeding source was identified. Although the patient initially recovered well, he developed recurrent aSDH one week later. Digital subtraction angiography (DSA) subsequently identified a saccular aneurysm arising from the accessory meningeal artery. Endovascular coil embolization achieved complete aneurysm occlusion with no further recurrence, and the patient remained neurologically intact. This case highlights that ruptured AMA aneurysms may remain occult despite negative CT angiography and should be considered in unexplained or recurrent nontraumatic aSDH. Early DSA is essential for definitive diagnosis, and prompt endovascular treatment can prevent recurrence and achieve favorable neurological outcomes.
INTRODUCTION
Acute subdural hematoma (aSDH) is a critical neurosurgical emergency typically resulting from high-energy head trauma that causes the laceration of bridging veins between the cerebral cortex and the dural sinuses [6]. While trauma remains the most common etiology, spontaneous or nontraumatic aSDH is a rare clinical entity, accounting for a small percentage of cases [8]. These spontaneous events are often associated with vascular malformations, coagulopathies, or the rupture of aneurysms into the subdural space [3,8].
Aneurysms arising from the external carotid artery distribution, specifically the middle meningeal artery (MMA), are exceedingly rare causes of aSDH [3,8]. Although the MMA is a primary supplier of the dura mater, its anatomical variations—including the accessory meningeal artery (AMA)—can lead to unique clinical presentations [4]. The AMA typically originates from the maxillary artery or the MMA itself and enters the cranium through the foramen ovale [1,4]. While aneurysms of the main trunk of the MMA have been documented as rare causes of acute epidural or subdural hemorrhage, pseudoaneurysms or true aneurysms of the accessory MMA are even more infrequent [8,11]. In fact, reports of nontraumatic aSDH secondary to an accessory meningeal artery aneurysm are exceptionally rare, with only one previously documented case in the literature [8].
The clinical management of these cases is further complicated by the potential for recurrence. Unlike typical traumatic aSDH, where surgical evacuation and hemostasis usually prevent re-accumulation, bleeding from an unrecognized meningeal aneurysm can lead to atypical postoperative recurrence [11]. This underscores the critical importance of diagnostic digital subtraction angiography in cases of unexplained or recurrent subdural hematoma to identify underlying vascular anomalies [3].
This case report describes a unique and rare occurrence of recurrent aSDH associated with a spontaneous aneurysm of the accessory meningeal artery. We discuss the diagnostic challenges, the role of advanced imaging, and the successful management of this rare vascular pathology.
CASE DESCRIPTION
A 36-year-old male with underlying hypertension presented with a one-week history of progressive, worsening headache. The headache was holocranial, throbbing in nature, worse in the morning, and associated with nausea and blurring of vision. He denied any history of trauma, falls, or acceleration-deceleration injuries. There was no history of anticoagulant or antiplatelet use, no known coagulopathy, no history of seizures, and no prior neurosurgical intervention. He also denied any symptoms suggestive of underlying vascular malformation, such as focal neurological deficits or prior episodes of unexplained headache.
The patient was initially well-appearing at home despite the headache. However, his family noted that he became progressively drowsy over the course of the day prior to arrival. Upon arrival at our emergency department, the patient was drowsy but remained oriented to time, place, and person. He was able to obey two-step commands. His blood pressure on admission was 178/85 mmHg, and he was started on parenteral antihypertensive. There were no focal neurological deficits on examination; specifically, there was no pupillary asymmetry, no motor or sensory deficits, and no signs of meningism. Blood investigations were normal, with no thrombocytopenia or coagulopathy.
Non-contrast computed tomography (CT) of the brain demonstrated a left convexity acute-on-chronic subdural hematoma (ACSDH) with a thickness of 1.1 cm and a midline shift of 0.9 cm (Fig. 1). Otherwise, there was no fracture seen or any evidence of trauma. CT angiography (CTA) was performed and revealed no vascular malformation (Fig. 2). Because of the patient’s progressive drowsiness and significant mass effect on CT, emergency decompressive craniectomy and hematoma evacuation were prioritized over preoperative digital subtraction angiography (DSA) to avoid delaying life-saving surgical decompression.
Initial non-contrast CT of the brain. (A) Axial CT image demonstrating a left convexity acute-on-chronic subdural hematoma causing significant mass effect and midline shift. The red arrow indicates the mixed-density hematoma, comprising acute hyperdense and subacute-to-chronic hypodense components, while the red curved line outlines the extent of the subdural collection. (B) CT image confirming the left convexity acute-on-chronic subdural hematoma with associated mass effect. The red arrow indicates the mixed-density hematoma, and the red curved line delineates the extent of the subdural collection. CT, computed tomography
Initial vascular imaging. CTA of the intracranial circulation demonstrating no obvious vascular malformation, aneurysm, or active contrast extravasation to explain the spontaneous hemorrhage. CTA, computed tomography angiography
The patient underwent an emergency decompressive craniectomy with evacuation of the acute subdural clot. Intraoperatively, no abnormal cortical vessels, vascular malformation, or active bleeding source was identified in the surgical field (Fig. 3). Fascioduroplasty was done, and bone wasn’t replaced given the degree of cerebral edema. The surgical exposure was limited to evacuation of the convexity subdural hematoma and did not extend to the skull base or middle cranial fossa floor, where the accessory meningeal artery enters the cranial cavity through the foramen ovale.
Intraoperative findings during decompressive craniectomy and hematoma evacuation. (A) Intraoperative view following dural opening demonstrating evacuation of acute subdural clot over the cerebral convexity. No obvious abnormal cortical vessels, vascular malformation, or active arterial bleeding source was identified. (B) Following complete hematoma evacuation, the cortical surface appeared adequately expanded. No abnormal cortical vessels, vascular malformation, or other apparent source of hemorrhage was observed intraoperatively.
Postoperatively, the patient recovered well. He became alert and had no focal neurological deficits. Immediate postoperative CT brain demonstrated satisfactory evacuation of the hematoma with improvement in mass effect and adequate cerebral re-expansion (Fig. 4).
Immediate postoperative imaging following decompressive craniectomy and hematoma evacuation. Coronal non-contrast CT brain performed following decompressive craniectomy demonstrating satisfactory evacuation of the left convexity acute subdural hematoma with improvement in mass effect and adequate cerebral re-expansion. CT, computed tomography
DSA was planned following postoperative stabilization to investigate the spontaneous nature of the hemorrhage. However, while awaiting DSA to investigate the spontaneous nature of the hemorrhage, the patient developed a sudden severe headache approximately one week after surgery. On examination, the craniectomy site, which had previously been soft, became firm. A repeat CT brain demonstrated a new aSDH, which was thicker and localized predominantly over the middle cranial fossa (Fig. 5). Otherwise, there was no neurological deterioration, and the patient remained Glasgow Coma Scale (GCS) 15 with no focal deficits.
Postoperative recurrence of acute subdural hematoma. Coronal non-contrast CT brain performed 7 days after initial surgery following recurrence of symptoms demonstrating interval re-accumulation of acute subdural hematoma over the left cerebral convexity, predominantly involving the temporal region and middle cranial fossa (circle), associated with recurrent mass effect. CT, computed tomography
Given the recurrent spontaneous hemorrhage, DSA was pursued one week after recurrence when the patient was neurologically stable. DSA revealed one saccular aneurysm arising from a branch of the MMA, specifically the AMA. The lesion was considered the most likely source of both the initial and recurrent hemorrhages, as it represented the only identifiable vascular abnormality (Fig. 6). The aneurysm was successfully treated with endovascular coil embolization, achieving complete occlusion of the aneurysm-bearing distal accessory meningeal artery with no residual contrast filling of the aneurysmal lesion (Figs. 7 and 8).
Pre-embolization DSA demonstrating the accessory meningeal artery aneurysm. (A) Selective left ECA angiography in the AP projection demonstrating a saccular aneurysm (arrowheads) arising from a distal branch of the left accessory meningeal artery. (B) Selective left ECA angiography in the lateral projection confirming the aneurysm (arrowheads) and its origin from the accessory meningeal artery. (C) Superselective digital subtraction angiography of the left accessory meningeal artery in the AP projection providing detailed visualization of the saccular aneurysm (arrowheads) prior to endovascular treatment. (D) Superselective digital subtraction angiography of the left accessory meningeal artery in the lateral projection confirming the aneurysmal lesion (arrowheads) and parent vessel anatomy before coil embolization. AP, anteroposterior; DSA, digital subtraction angiography; ECA, external carotid artery
Endovascular coil embolization of the left accessory meningeal artery aneurysm. (A) AP roadmap image demonstrating superselective microcatheterization of the left accessory meningeal artery with deployment of detachable coils (arrowheads) into the aneurysm-bearing distal accessory meningeal artery. The procedure involved coil embolization with occlusion of the parent vessel rather than selective coil embolization of the aneurysm sac alone. (B) Lateral roadmap image confirming appropriate microcatheter position and coil deployment (arrowheads) within the aneurysm-bearing portion of the left distal accessory meningeal artery prior to completion of embolization. AP, anteroposterior
Post-embolization angiographic assessment following coil embolization of the left accessory meningeal artery aneurysm. (A) AP and (B) lateral left ECA DSA obtained immediately after embolization demonstrate complete exclusion of the aneurysm with expected occlusion of the aneurysm-bearing distal accessory meningeal artery, with preservation of normal external carotid artery branches and no evidence of residual aneurysm filling or contrast extravasation. (C) AP and (D) lateral superselective completion angiograms of the left accessory meningeal artery confirm complete occlusion of the aneurysm with absent residual contrast opacification. The microcatheter remains in position during the final angiographic check run, confirming successful endovascular embolization. AP, anteroposterior; ECA, external carotid artery; DSA, digital subtraction angiography
The procedure was well tolerated, and no periprocedural complications occurred. The patient remained neurologically intact following embolization, and he was discharged well on post-embolization day 3. At 3-month follow-up, he was asymptomatic and neurologically intact, with no clinical evidence of trigeminal nerve dysfunction or other neurological sequelae related to AMA parent artery occlusion. He was then scheduled for elective cranioplasty once the craniectomy site was suitable for bone flap replacement.
DISCUSSION
Spontaneous aSDH is a rare clinical entity, accounting for approximately 2.0% to 6.7% of all aSDH cases [8]. Unlike the typical traumatic etiology involving the tearing of cortical bridging veins, nontraumatic aSDH necessitates the investigation of underlying vascular pathologies such as coagulopathy, arterial rupture, or vascular malformations [6,8]. Among these, hemorrhage originating from the meningeal circulation—particularly an accessory meningeal artery—is exceedingly rare, with most literature focusing on the main trunk of the middle meningeal artery [3,8].
The accessory meningeal artery is a notable anatomical variant that typically originates from the maxillary artery and enters the cranium through the foramen ovale rather than the foramen spinosum [4]. It provides critical supply to the trigeminal ganglion and the dura of the middle cranial fossa [1].
Pathophysiology of aSDH from an AMA Aneurysm
The mechanism by which an AMA aneurysm produces subdural rather than epidural hemorrhage is rooted in distinct anatomical and microstructural differences from the MMA. The MMA enters the cranium through the foramen spinosum and runs within a bony groove on the inner table of the skull, rendering it tightly adherent to bone; thus, its rupture typically strips the dura from the calvarium, resulting in an epidural hematoma [3]. In contrast, the AMA enters via the foramen ovale and is predominantly an extracranial vessel, with only a minor branch supplying the dura of the middle cranial fossa and the trigeminal ganglion [2]. This intracranial branch lies within the dural layers rather than against bone [8]. Consequently, when an AMA aneurysm ruptures, high-pressure arterial blood may extravasate directly into the dural vascular plexus (DVP)—a rich capillary network located within the dural border cell layer [5]. Disruption of this plexus may lead to dissection within the dural border cell layer, creating a subdural hematoma rather than an epidural collection. This mechanism is supported by the only other reported case of spontaneous aSDH from an AMA pseudoaneurysm [8] and explains the predominant localization of recurrent bleeding over the middle cranial fossa observed in our patient, consistent with the AMA’s primary intracranial territory [2].
Pathophysiology of recurrence
Several mechanisms may explain the recurrent hemorrhage observed in the present case. The accessory meningeal artery aneurysmal lesion identified on DSA was considered the most likely bleeding source based on its anatomical correlation with the recurrent hematoma and the absence of further hemorrhage following endovascular embolization. Although postoperative iatrogenic pseudoaneurysm should also be considered, we believe this explanation is less likely. The patient initially presented with spontaneous nontraumatic aSDH before any surgical intervention, and DSA demonstrated no vascular abnormality other than the accessory meningeal artery aneurysmal lesion. Furthermore, the accessory meningeal artery enters the cranial cavity through the foramen ovale and courses along the skull base, anatomically remote from the frontotemporoparietal decompressive hemicraniectomy and dural opening performed in our patient, making direct operative injury unlikely. Finally, complete angiographic exclusion of the lesion resulted in no further hemorrhagic recurrence during follow-up. Nevertheless, because the lesion was not demonstrated on the initial CTA and no preoperative DSA was performed, a postoperative pseudoaneurysm cannot be completely excluded.
Although the spatial distributions of the initial and recurrent hematomas differed—with the initial hematoma distributed broadly over the cerebral convexity and the recurrent hemorrhage localized to the middle cranial fossa—this topographic variation likely reflects the AMA’s primary dural territory and the influence of gravity on subdural blood dispersion rather than indicating distinct bleeding sources. The AMA’s intracranial branch supplies the dura of the middle cranial fossa, which anatomically correlates with the recurrent hemorrhage’s predominant localization. The AMA lesion was the only vascular abnormality identified on comprehensive DSA, and its complete occlusion resulted in no further hemorrhage, supporting it as the most likely source of both bleeding episodes.
The pathophysiology of recurrence in this case is likely driven by the inherent instability of the aneurysm combined with systemic risk factors. Although hypertension has been reported in several cases of spontaneous meningeal artery aneurysms, the underlying pathogenesis remains uncertain and is likely multifactorial. Hypertension may represent one of several contributing factors rather than an independent causative mechanism [9]. If the arterial source is not identified and obliterated during initial surgical evacuation, the persistence of this high-pressure leak leads to the atypical postoperative recurrence seen in this patient [3].
Diagnostic challenges
A significant diagnostic challenge in managing meningeal aneurysms is the potential for false-negative findings on initial non-invasive imaging. CTA often lacks the sensitivity to detect small or vasospastic meningeal lesions [3]. CTA may fail to identify small meningeal artery aneurysms because of several factors. In addition to the small caliber of the accessory meningeal artery and the limited spatial resolution of CTA, transient vasospasm, slow flow within the aneurysm, and compression of the parent vessel by the surrounding hematoma may reduce contrast opacification, resulting in false-negative findings. Consequently, DSA remains the gold standard for definitive diagnosis, as it allows for the precise visualization of the AMA’s origin and morphology [1,3]. Clinicians should maintain a high index of suspicion and proceed to DSA in cases of unexplained or recurrent aSDH, even when initial CTA findings are negative [3,8]. In the present case, no interval MRI was performed between the initial surgery and recurrent hemorrhage. Because recurrent hemorrhage occurred despite a negative CTA, DSA was performed directly as the gold standard for identifying occult vascular lesions and to facilitate definitive diagnosis and treatment.
Review of the literature
A literature review was performed using PubMed and Google Scholar from database inception through June 2026 using the search terms “accessory meningeal artery aneurysm,” “middle meningeal artery aneurysm”, “pseudoaneurysm”, and “acute subdural hematoma.” English-language case reports describing intracranial hemorrhage associated with meningeal artery aneurysms were included.
Review of the current literature reveals that nontraumatic aSDH specifically caused by an accessory meningeal artery aneurysm is almost unique. To date, only one other case has been explicitly documented in medical literature [8], making the present case only the second reported instance of AMA-related aSDH and the first to describe recurrent hemorrhage. While broader series have identified spontaneous arterial aSDHs (e.g., 10 cases in a series of 149), the vast majority involve the main MMA or cortical arteries [7,13]. Previously reported cases of accessory meningeal and middle meningeal artery aneurysms presenting with intracranial hemorrhage are summarized in Table 1.
Published cases of meningeal artery aneurysms presenting with intracranial hemorrhage
Clinical implications and treatment
The clinical implications of this case highlight a shift toward endovascular management. While surgical evacuation is necessary for symptomatic mass effect, endovascular embolization of the AMA/MMA is increasingly recognized as a definitive treatment to prevent recurrence. A systematic review reported complete occlusion of meningeal (pseudo-)aneurysms in all patients following endovascular embolization, with symptomatic improvement in 90.32% (28 of 31 patients). Persistent mild symptoms, such as mild hemiparesis, occurred in only three patients, and complications were rare (<5%) and mild—typically transient headaches [10].
The AMA is an anatomically significant vessel that provides vascular supply to the trigeminal ganglion, the dura of the middle cranial fossa, and the gasserian ganglion, with potential anastomotic connections to the cavernous sinus and the petrous carotid artery via skull-base collaterals [1,2]. Parent artery occlusion of the distal AMA, as performed in this case, carries potential theoretical risks, including ischemia to the trigeminal nerve territory and compromised dural vascularity. However, the rich collateral network of the external carotid artery system, including anastomoses with the contralateral AMA, the middle meningeal artery, and the ascending pharyngeal artery, typically provides adequate compensatory blood flow [1,4]. Complete occlusion of the aneurysm-bearing distal AMA was achieved without any neurological complications, and the patient remained asymptomatic at 3-month follow-up. This approach aligns with the current endovascular paradigm for treating distal meningeal artery aneurysms, where parent vessel sacrifice is generally well-tolerated due to robust collateral circulation [10]. Nevertheless, clinicians should be aware of the AMA’s crucial anatomical relationships when planning endovascular intervention, particularly its proximity to the foramen ovale and the trigeminal ganglion.
Early identification via DSA followed by targeted embolization can effectively devascularize the source of hemorrhage and stop the cycle of recurrence that characterizes these rare arterial presentations.
CONCLUSIONS
Spontaneous aSDH associated with an accessory meningeal artery aneurysmal lesion, which we identified as the most likely bleeding source for both the initial and recurrent hemorrhages, represents an exceptionally rare vascular entity and an important diagnostic challenge. To our knowledge, this is the first reported case of recurrent aSDH attributed to an AMA aneurysm, with only one other case of AMA-related aSDH documented in the literature. This case highlights that underlying meningeal vascular lesions should be strongly considered in patients presenting with nontraumatic or recurrent aSDH, particularly when intraoperative findings are inconclusive, or hemorrhage recurs unexpectedly following surgical evacuation.
Negative computed tomography angiography does not exclude an occult vascular etiology, and digital subtraction angiography remains the gold standard for definitive diagnosis. Early recognition of this rare condition followed by targeted endovascular embolization can successfully eliminate the bleeding source, prevent recurrence, and achieve favorable neurological outcomes.
Notes
Consent to participate
Written informed consent was obtained from the patient for inclusion in this case report and for publication of the accompanying clinical data and figures.
Funding
No financial support was received for the research, authorship, or publication of this manuscript.
Disclosures
The authors report no conflict of interest concerning the materials or methods used in this study or the findings specified in this paper.